﻿// Jinx AJAX Framework
// Copyright (C) 2008 Blake Hegerle
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Formality.FormalSystem.Parser
{
    public class Bindings
    {
        public Bindings()
        {
            BindingMap = new Dictionary<string, int>();
        }

        public int this[Variable Variable]
        {
            get
            {
                int BindingNumber;

                return BindingMap.TryGetValue(Variable.Name, out BindingNumber) ? BindingNumber : 0;
            }
            set
            {
                BindingMap[Variable.Name] = value;
            }
        }

        public void Bind(Variable Variable)
        {
            this[Variable]++;
        }

        public void Unbind(Variable Variable)
        {
            var BindingNumber = this[Variable];

            if (BindingNumber > 1)
                this[Variable] = BindingNumber - 1;
            else
                BindingMap.Remove(Variable.Name);
        }

        private Dictionary<string, int> BindingMap;
    }
}
